Hydraulic speed governor with manual control



July 13, 1965 R. B. LocHER, JR., ETAL 3,194,252

HYDRAULIC SPEED GOVERNOR WITH MANUAL CONTROL Filed May 22. 1961 2 Sheets-Sheet 1 llllll Il Bigras-f July 13, 1965 R. B. LocHER, JR., ETAL 3,194,252

HYDRAULIC SPEED GOVERNOR WITH MANUAL CONTRL Filed May 22. 1961 2 Sheets-Sheet 2 United States Patent O Romuald E. Locher, Er., Madison Heights, and George W.

Nicoletti, ltr., Ferndaie, Mich., assignors to ltolieyV Carburetor Company, Warren, Mich., a corporation of Michigan Fiied May 22, 1961, Ser. No. 111,625 ll Ciaims. (Ci. fwn-i3) The invention relates to governors and refers more specifically to vhydraulically controlled diaphragm actuated mechanism for positioning a speed control member.

Hydraulic governors have been known in the past for use in conjunction with vehicle mounted internal combustion engines and similar devices for regulating the Vehicle or engine speed. Prior hydraulic governors have however often been relatively complicated whereby the governors have been expensive and often unreliable.

It is therefore one of the objects of the present invention to provide improved hydraulically controlled diaphragm actuated mechanism for positioning a speed control member.

Another object is to provide a governor comprising hydraulic control means, diaphragm actuating means responsive to the hydraulic control means, and mechanism for positioning a speed control member responsive to the diaphragm actuating means.

Another object is to provide a governor as set forth above wherein the hydraulic control means comprises a speed sensing unit, a hydraulic fluid supply tank, a first circulating circuit for hydraulic fluid from the fluid supply tank through the speed sensing unit to the diaphragm actuating means and back to the fluid supply tank, a second hydraulic fluid circulating circiut from the fluid supply tank to the diaphragm actuating means and back to the uid supply tank, means for pumping hydraulic fluid from the supply tank through the circulating circuits, means for rotating a portion of the speed sensing unit at a speed proportional to the speed to be governed, and means for restricting the ilow of hydraulic iiuid through the speed sensing unit in accordance with the speed of rotation of said portion thereof.

Another object is to provide a governor as set forth above wherein the diaphragm actuating means comprises two diaphragm assemblies, each including a pair of housing members having a diaphragm clamper therebetween whereby separate chambers are formed on opposite sides of the diaphragm, a governor actuating rod secured to each of the diaphragms and extending through openings in one of the housing members of each assembly, the chamber formed between the diaphragm and said one diaphragm housing member of each assembly being opened to atmospheric pressure, means for supplying hydraulic uid under pressure to one of the diaphragm assemblies on the opposite side of the diaphragm thereof from the actuating rod directly from the iiuid supply tank, means connecting the chamber on the opposite side of the diaphragm of the other diaphragm assembly to the hydraulic fluid pumped through the speed sensing unit, said other diaphragm assembly including resilient means urging the actuating rod therein toward said one diaphragm assembly, and means connecting each of the chambers on the said opposite side of the diaphragms to the hydraulic fluid supply tank through restrictions.

Another object is to provide diaphragm actuating means as set forth above wherein the chambers on said opposite side of the diaphragms are interconnected through a restriction.

Another object is to provide diaphragm actuating means as set forth above wherein the chamber on the opposite side of the diaphragm of said one diaphragm assembly Patented .iuiy i3, i965 ICC is connected directly to the hydraulic fluid supply tank through a restriction.

Another object is to provide a hydraulic governor as set forth above wherein the mechanism for positioning a speed control member comprises a shaft mounting the speed control member for rotation therewith, a drive member rigidly secured to one end of the shaft having an abutment thereon, spring means urging the drive member in a direction to move the speed control member to an open position, a lever pivotally mounted on the one end of the shaft having an abutment thereon engageable with the abutment on the drive member, spring means urging the lever in a direction to cause engagement of said abutments, and means for manually positioning said lever, the last mentioned spring being stronger than the first mentioned spring, a drive member secured to the other end of said shaft for rotation therewith having an abutment thereon, a lever pivotally mounted on said other end of said shaft having an abutment thereon engageable with the abutment on the last mentioned drive member when the lever is pivoted in a direction to close the speed control member, which last mentioned lever is pivotally connected to the actuating rods for movement thereby to limit movement of the speed control member in an opening direction in .accordance with the speed sensed by the speed sensing unit.

Another object is -to provide a hydraulic governor which is simple in structure, economical to manufacture and efficient in use.

Other objects and features of the invention wil-l become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

FGURE 1 is a partly diagrammatic, partly schematic illustration of one embodiment of the hydraulic governor of the invention.

FIGURE 2 is a fragmentary diagram of a modification of the hydraulic governor illustrated in FIGURE l.

FiG-URE 3 illustrates a modified diaphragm assembly for use in a hydraulic governor as shown in FIGURE l.

`With particular reference to the figures one embodiment of the present invention will now be disclosed.

As shown in FIGURE l the hydraulic governor of the invention comprises `the hydraulic contr-ol means iti, diaphragm actuating means l2 and the mechanism 14 for positioning the throttle i6 to control the speed of the engine i7. In operation the speed of the engine l? which it is desired to govern is sen-sed by the speed sensing unit @il of the hydraulic control means. The diaphragm assemblies 2@ and Z2 of the diaphragm actuating means are caused to position the rods 2d and 26 in accord-ance with the sensed speed and the mechanism ltd is caused to limit the position of the throttle i6 in accordance with the position of the rods 2d and 26 through the lever member Sti and drive member 32 acting on throttle shaft 2S.

More specifically the throttle valve 16 is rotatably mounted in the induction passage 34 of a carburetor 36 mounted on the intake manifold 3S of internal combustion en ine 17. As shown in FIGURE l rotation of the throttle valve 16 in a clockwise direction will open the induction passage 3d of the carburetor 36 and therefore increase the speed of the engine with which the carburetor is associated. Rotation of rthe throttle valve lo in a counterclockwise direction will close the throttle valve 16 to reduce the speed of the engine associated therewith.

rfhe hydraulic control mean-s l@ includes a speed sensing unit dii, a hydraulic duid supply tank ill and a gear pump l2 for pump-ing hydraulic iiuid from the tank 41 to the speed sensing unit it? through conduit d4 and to the diaphragm assembly hydraulic fluid, fluid supply tank and pump could in a specific system be motor oil, an engine cra-nkcase andV engineoil pump respectively.` A bypass conduit 48 is. vprovided'between the outlet conduit50 of the pump 42k and the pump inlet conduit V52 from the hydraulic fluid supply tank 41 in which is positioned Va lconstant pressure relief valve V54 .so vthat the hydraulic fluid delivered to conduits 44 and 46 through. conduit 50 fromy pump 4Z- L is always atV a constantf predetermined pressure P1.

Hydraulic conduits 56 and 58 are connected between the speed sensing unit 40 and the hydraulic fluid supply tank 41 and between ythe hydraulic speed sensing uni-t 40 and the diaphragm assembly respect-ively, as illust-rated.`

22 through conduit 4a.V The j .'phragm'ltM Iandthe frictional resistanceito .movement of the rods -24 and 26 'oiferediby the pivot"pinr114 and; the pivot-ally'mounted lever 31H0' which the'jpivotpin 114 therein and a passage72 extending therethrough.' A shaft Y some function of the speediof theenginev is supportedwithin the passage 72 bymeans of bearings 7 6. An axial passage 78 through the shaft 74 is in communication at end 80 thereof with an annular passage 82 in housing 68 in which the* conduit 44 terminates. Passagey 787i is in communication at thepother end there-of with the conf duit 58.` A lh'ollow cross arm 34 is provided on shaft. 74

within the chamber '70 and includes therein a valve member S6 positionable within the ypassage SSof the crossarm 84 in accordance ywith the speed of rotation of i shaft 74 'due lto centrifugal force acting thereon. The

spring 90` is provided t-o urge the valve member 86 to the 74 rotatable at the speed of the engine to be governed or;

left, Yas shown rin FIGURE l, into engagement with the f yadjustable abutment 92.

Y In operation on rotation ofy shaft 74'at a speed determined by the adjustment Yof the abutment 92V and the compression inthe spring due to adjustment of abutment 94 centrifugal force acting on .the valve member 86 will cause the valve to move to `the'right, as illustrated in FIG- URE' 1, in opposition to the bias ofthe spring .90.to' re-V- `strict'the passage 78 through the shaft 74. i `The passages 96 and 98 -through'the valve 186prevent locking of the f valve 86 'in a predetermined position due tov trapped hydraulic iiuid. Y Thus it will be seen that after the .speed has been' reached at which the valve 86 partially closes'the passagesy 78 through the shaft 74 that the'pressure in conduitSS will be vat some lower pressure P2 than the pressure P1- in the conduit 44. Further this pressure difference will bev proportional to the restrictionof the passage 78 by the valve 86 and therefore will be proportional to the speed of rotation of shaft 74.

The diaphragm assembly'ZZ of the diaphragm yactuating means 12 comprises the separate housing members 100 I and ltlzwhich may be generally circular in transverse cross section and which have the circular diaphragm-104- @G0 clamped therebetween. Rod p26 .is secured to diaphragm l 1041by conventional means such as plates 106 and 108'4 `at end 110 and is pivoted tov the lever member 30 atthe end 112 by pivot meansV 1.14.

Opening 116 is provided in housing member 1027in-to which. conduit 46V is connected so that chamber 118 2 formed by the housing member 102 and diaphragm 104 t has pressure P1 therein at any time pump 42 .is operating.

Opening 120is als-o provided in the housing 102 into 1 which `restricted conduit .60 is connected. As previously indicated vrestricted conduit 60 connects chamber 118 to .chamber 136 to prevent trapping of air in chamber 118.

The diaphragm assembly 20 is similar to the diaphragm assembly 22 ;as `regards the housing members 124 and y 126 and the diaphragn1.128 and rod 24. The diaphragm assembly 20 is however-also provided .with a spring 132 oper-able between lthe mounting plate 134 torqrod 24and housing member' 126 @to urg-etheqrod 24 to the left,as

shown in FIGURE V1,V at anytmethepressure differentialVV .across the Vdiaphragm 128 plu-s the'b'ias of the spring 132 is greater. than the pressure diiferen-tial'across the diais` secured. Y

The openings-130'138 `'and"14t Aare-1provided inrthe housing member 12j6aof the diaphragm l.assembly 2i) for connecting the conduits. 60,' 58 and :62; respectively,r into.YV

chamber'136'.

The mechanical apparatus 14'for`positioning thetthrottle .Y 16 compri-ses the. lever member 30. pivotally mounted .onl -Y the 'throttle shaft ZS'OrrOt-ationvbythe rods 24 andf26 and drive member 32.ri'gidlyrsecu'red tothe throttle shaft 28. v Lever. meinb`er130 as illustrated is providedfwithpthe abutment 142 which in` operation :fisfen'gageablej with' lar Y similar a-butmentz144- on .the `driver'riember" 32 l on counter-V i clockwise rotation ofy the -lever :member 30.' Countefr-V i `clockwise rotation of nlevierI member 30.,.thus causes 'rota- `tion of throttle 16 in aV closed direction whilegcloc'kwise.

rotation of the llever mem-be'r30 cau-ses theY abutments 142 and V144 to separate and does @retient-.the positioning of the throttle 16,;iat speedsbelowV governing `.speedx at which 'time the'throttle is ycontrolled bythe drive memf. ber 146 and lever. .148 at ,the opposite. end fof `.throttleshaf-t 28,.

' Drive .member Lever. 143 ispivotally mounted onshaft @2S and Ais proy vided with abutment 152l 'enga-geable vwith .a similar'arbutment 154 onV drive member ,146 (on counterclockwise rotation of leveri143.y The manualithrottle-1linkage 156 is pivotally `secured to'lever- 148.10v position the lever 148 inl opposition to the. bias of spring 158 to regulate the opening .of the throttle' 16 by spring .150 tat speeds below govi erningV speed.. Spring .150 Vis lighter than spring lits'so-V that the .throttle v16 is biased 'in -.a closed direction and ymust be opt-' :knedL manuallythrou-gh linkagem156. VAt govrV Y erning` speed the' counterclockwise ,rotation of .throttle :shaft ZSUbyYdriy'e member 32 engaged with" lever 30 causes closing of theV throttle 16 in oppo-siti'onto spring and consequentseparation of abutments- 1.5.4y and ,1522 V Y In over-all oper-ation of the governor it willfbe assumed that the governor governs the speed .of Ythe engine1l17," through control of the` position :of thethrottle 16 andthat initially the engine isoperating ata speed below the gov.

erned speed- 'thereof-` `AtV this timefthe pump 42,will beV oper-ating so that pressure P1' isV present Vin' conduit V50'.'

The `shaftl74 -is rotated .at the speed. of theengine, however the valve86ris` in'its` leftward limiting positionas illustrated due to the bias/applied thereto by thev springil` The pressure in lconduit 46 and therefore in'chamber 1t8, of diaphragm assembly 2-2Laud1the'pre'ssuresin conduit 44, passage 78,1 conduit 58,-fandtherefore .in chamber 13.6 of diaphragm assembly 20 issthepressure'Plin' conduit 50.

Since the chmnbersf 160 sand- 162 on the. other. side of the'diaphragms 104 and 128 from thechambers 118 and 136 respectively are open :to atmo-sphere thefrods; 24'and 26 areV at this'tirne in a leftward limiting position due to thebias' Ofspring132.. Lever v30 is therefore ,in a fully clockwise position and 'abutments 142' and 144 are kdis-` engaged.A No governing action yistherefore present at this time. p Y

The speedrof the engine isgat this time controlled by the manual linkage 156, pivoting 1ever"148rin a clockwise di rection against the biasof'spring'-158whereby theweaker spring 150 is permitted torotate .therdrive member. 146

and the shaft 28 until `the abutment-s154 .and i152 are in: engagement. Thus inthe; usual manner below` governed.

issie rigid-1y .muretto shaft 2s V'for rotation .therewith and is biased by means of spring Y150 Iin acl'ockwise'direction tojcause opening ofth-r-ottle 16,);

speed the throttle valve 16 is positioned in accordance with the position `of a manually actuated linkage 156.

At the speed at which governing is initiated the centrifugal force developed on rotation of shaft 74 at this speed causes 'movement of the valve S6 to the rig-ht in FIGURE l in opposition to the bias applied to valve 36 by spring 9) so that ,the valve 86 restricts the passage 78. Restriction of the passage 7S produces the lower pressure P2 in conduit 58 and therefore in chamber 136. Pressure P1 is still maintained in chamber 11S however since the restriction 64 in conduit 6u connecting chambers 118 and 136 is very small. Thus as t-he speed of the engine approaches governed speed the pressure difierential across the diaphragm M is suiiiciently larger than the pressure differential across the diaphragm 123 to cause movement of the diaphragms and the rods Z4 and 26 connected thereto to the right in FIGURE l.

As previously indicated movement of the rods 24 and 26 to the right in FIGURE l causes counterclockwise rotation of lever member 3) so that the abutments 142 'and 144- on the lever member 36 and drive member 32 respectively engage. Engagement of the abutments 142 and 144 will cause counterclockwise movement of throttle 16 through shaft 23 on subsequent counterclockwise rotation of the lever member 3%. Such counterclockwise movement of the throttle 16 will of course cause disengagement of the drive member 146 and the lever 148 so that engine speed will now be under the control of the governing mechanism. As the engine speed increases to the governed speed of the engine rotation of the shaft 74 increases and the restriction of passage 78 is more pronounced so that pressure P2 is related to pressure P1 to position the rods 24 and 26 and lever member 30 so that the throttle 16 is permitted to open only far enough to sustain the governed engine speed.

The conduit 69, as previously mentioned, is provided only as a means for bleeding any air trapped in chamber 118 back to the hydraulic fluid supply tank 4t) and therefore the restriction 64 in the conduit 6) may be extremely small and will have little effect on the pressure differential between chambers 118 and 136 in the above indicated operation. In fact, as is shown in FIGURE 2, the conduit 62 may be connected directly back to the hydraulic uid supply tank 41 in a modiiied embodiment of the invention with the operation of the governor being the same as described above. Air which may be trapped in chamber 136 is removed through the outlet conduit 62 having restriction 66 therein connected as shown. Conduit 62 also permits iow of hydraulic l'luid through the chamber 136 which -is necessary to create the pressure difference between P1 and P2.

The governing action after the speed at which governing is initiated is reached may be controlled by varying the force exerted on diaphargm 123 by the spring 132 if desired. Thus as illustrated in FIGURE 3 the diaphragm assembly 2? may be provided with a movable abutment 164 against which end 166 of spring 132 is positioned.. The speed at which governing action is initiated may be controlled by the variable abutment 9d against which spring 99 of the speed sensing unit 10 is positioned in conjunction with variable positioning of the adjustable abutment 92.

Thus it will be seen that in accordance with the invention there is provided a simple eiicient hydraulically controlled diaphragm actuated mechanical apparatus for positioning a speed control member. While one complete embodiment of the hydraulic governor of the invention has been disclosed and modifications thereof indicated, it will be understood that other modications thereof are contemplated and are intended to be included within the scope of the invention.

The drawings and the foregoing specification constitute a description of the improved hydraulic speed governor in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

1. A governor for an internal combustion engine or similar device having a speed control member such as a throttle mounted on a rotatable shaft, comprising iirst mechanism for positioning the speed control member at speeds above a predetermined speed including a first drive member rigidly secured to one end of the shaft and having an abutment thereon extending axially outwardly of the shaft, and a first lever member pivotally mounted on the one end of the shaft and having an abutment thereon extending axially inwardly of the shaft and overlapping the abutment on the drive member, said abutments being engageable on rotation of said rst lever in a direction to cause closing of the throttle, said governor further including second mechanism for positioning the speed control member at speeds below the predetermined speed including a second drive member rigidly secured to the other end of the shaft and having an axially outwardly extending abutment thereon, a second lever member pivotally mounted on the other end of the shaft and having an abutment thereon extending axially inwardly of the shaft and overlapping the abutment on the second drive member, said abutments on the second members being engageable on rotation of said second drive member in a direction to cause opening of the throttle, means pivotally secured to the Second lever kmember for applying a pivotal force thereto, bias means secured to said second lever member urging the second lever member in a direction to engage the abutment thereon with the abutment on the second drive member and cause closing of the speed control member and second bias means weaker than the first bias means urging the second drive member in a direction to open the throttle, diaphragm actuating means operably associated with said lirst mechanism for pivoting the tirst lever member in accordance with a difference in hydraulic pressure applied thereacross and hydraulic control means operably associated with said diaphragm actuating means for regulating the hydraulic pressure differential applied to the actuating means in accordance with the speed of the device.

2. Structure as set forth in claim 1 wherein the diaphragm actuating means comprises a pair of separate housings, each including two parts, a diaphragm clamped between the two parts of each housing forming a pressure chamber with one of the two parts and an actuating rod secured to each of the diaphragms at one end and pivotally connected in opposition to each other and to the first lever member at the other end and means for applying the pressure difference between the two pressure chambers.

3. Structure as set forth in claim 2 and further including a restricted conduit connecting the pressure chambers and a restricted conduit extending from one of the pressure chambers to the hydraulic control means.

4. Structure as set forth in claim 2 and further including a separate restricted conduit extending between each of the pressure chambers and the hydraulic control means.

5. Structure as set forth in claim 2 wherein resilient means are provided acting between one of the housings and the diaphragm therein for urging the piston rod connected thereto in a direction to pivot the iirst lever member to close the throttle Valve.

6. Structure as set forth in claim 5 wherein an adjustable plug is provided in the one housing in contact with said resilient means for varying the bias applied to the diaphragm inthe one housing by the resilient means.

7. Structure as set forth in claim 2 wherein the hydraulic control means includes a hydraulic fluid supply tank, a centrifugal speed sense including an outer housing and an inner rotor mounted for rotation within the outer housing having an axially extending passage therethrough and centrifugal valve means within said passage for restricting the passageV in accordance Withthe speed o'frotation` ofthe rotor, constant pressure pump means positioned bei., Y

actuating means operable to provide fluid at a substantial- Vlyconstant pressure in the pressure chamber in one ,of 'said housings in the hydraulic actuating means and at one'V end ofthe axial passage in the rotor, in `the hydraulic speed tween the hydraulicV fluid supply tank and the hydraulicv sense and means connecting `the other end of :the axial, 2Y passage in the rotor inthehydraulic speed sense'to the f other pressure chamber in the. other housing of the hydraulc actuating means whereby a diiference in hydraulic 'pressure is provided in the pressure chambers.' in accordance with the speed of rotation of said rotor.

8. Structure as set forth in claim 7 and further including means for varying the speed at which the valve means starts to restrict the, passage `through said rotor.

`chambers formedvin, the@` housings Ythe[diaphragmv actuating means;`

e 115A governor yfortan internal combustion engine or, l 'similar device having a` speed control membergsuchj as a: throttle, comprisingV mechanism gforfpo'sitioning the Vspeed controlmemberrat speeds :abovela predetermined'.V

speed, diaphragrnjactuating means operablylassociated with; said Vmechanismv `for' adjustingthe mechanism inV "accordanceiwith a difference between'hydraulic pressures applied thereto including a pair of.housings,-each including twoparts and having-a diaphragm clampedtherevbetween forming a pressure chamber between rthe `diag 9. Structure as set forth in claimS wherein the means- Y forvarying the speed at which the valve means starts to restrict the passage through said rotor comprises an adjustable Istop engaged with the valve member, resilient means engaged with said valve member urging it into engagement with the adjustable stop and an adjustable seat for said resilient means.V n

10.y A governor for an internal combustiontengne. or

similar device `having :a speed control member suchas,

a throttle, comprising mechanism for positioning the` speed control member at `speeds abovea predetermined speed, E; diaphragm actuating'means -operably associated with said mechanism for adjusting themechanism'in accordance with adiierence between hydraulic pressures Vapplied thereto including a pair of housing-s, each includ.-

ing two' parts andrhaving a diaphragm clamped thereabetween forming a pressure chamberbetweenthe ,dia-- phragm and one part of the housing and a piston rod. 'secured to the diaphragm and connected to the mecha- Y nism forpositioning the speed control` member and hy;

draulic control means operably associated withrsaid dia-' -1 phragm Vactuating means for regulating theglhydraulic pressurev difference applied to the actuating meansinl ac-` cordance with the speed of the device including `a hy,.k

draulic uid supply tank and a restricted exhaust passage extending-between one of said pressure chambers of `the diaphragm actuating means to the hydraulic fluidfsupply tank and a restricted conduit` connectingthe pressure Y phragmeandonepartqof the housing and a piston rod secured tothe-diaphragm'- and'connected to' themechanism for positioningthe vspeed control member` and hyf draulic:v control means operably associated with said diaphragm ,actuating means 'for vregulating jthe hydraulic pressure dilerential 'applied :to the actuating means in accordanceywith therspeed of thedevice including Va hydraulic' uid supply tank 'andra Yseparaterestricted eX-v haust passage, extendingbetweenfeach of ,saidypressurer chambers of` the diaphragm 'actuating;means Vand vthe hydraulic luidv Supply tank.`

References Citedby Vthe Examiner UNITED STATES PATENTS' 9/51 v Great Britain. i

ISADOR WEIL; PrmaryvExamrierJ Y Y M. CARY NELSON, CIARENCE Rf GORDON,-V

' Y Y Examiners. 

11. A GOVERNOR FOR AN INTERNAL COMBUSTION ENGINE OR SIMILAR DEVICE HAVING A SPEED CONTROL MEMBER SUCH AS A THROTTLE, COMPRISING MECHANISM FOR POSITIONING THE SPEED CONTROL MEMBER AT SPEEDS ABOVE A PREDETERMINED SPEED, DIAPHRAGM ACTUATING MEANS OPERABLY ASSOCIATED WITH SAID MECHANISM FOR ADJUSTING THE MECHANISM IN ACCORDANCE WITH A DIFFERENCE BETWEEN HYDRAULIC PRESSURES APPLIED THERETO INCLUDING A PAIR OF HOUSINGS, EACH INCLUDING TWO PARTS AND HAVING A DIAPHRAGM CLAMPED THEREBETWEEN FORMING A PRESSURE CHAMBER BETWEEN THE DIAPHRAGM AND ONE PART OF THE HOUSING AND A PISTON ROD SECURED TO THE DIAPHRAGM AND CONNECTED TO THE MECHANISM FOR POSITIONING THE SPEED CONTROL MEMBER AND HYDRAULIC CONTROL MEANS OPERABLY ASSOCIATED WITH SAID DIAPHRAGM ACTUATING MEANS FOR REGULATING THE HYDRAULIC PRESSURE DIFFERENTIAL APPLIED TO THE ACTUATING MEANS IN ACCORDANCE WITH THE SPEED OF THE DEVICE INCLUDING A HYDRAULIC FLUID SUPPLY TANK AND A SEPARATE RESTRICTED EXHAUST PASSAGE EXTENDING BETWEEN EACH OF SAID PRESSURE CHAMBERS OF THE DIAPHRAGM ACTUATING MEANS AND THE HYDRAULIC FLUID SUPPLY TANK. 